Abstract
The present paper experimentally investigates and analyses in detail the electrical characteristics of the arc for the hybrid pulsed micro-tungsten inert gas process. In particular, an average voltage–current (V–I) graph plotting approach is proposed to describe the dynamic characteristics of the hybrid arcs using the filtered voltage and current of the arc. It is shown that the average voltage and electrical resistance of the heavily hybrid pulsating (HHP) arc are lower than those of the slightly hybrid pulsating (SHP) arc, particularly during the background current stage. Furthermore, the analyses reveal that the average V–I characteristic graph for the arc forms a hysteresis loop, primarily because of the thermal inertia of the arc, during a pulse period. This closed loop is larger for the SHP arc than for the HHP arc, and shrinks longitudinally with increasing frequency and width of the current pulse. These results thus demonstrate that the HHP arc has a greater thermal inertia, particularly at higher current and pulse frequency. Experimental results show also that the mean voltage of the arc and the features of the hysteresis loop vary markedly with weld penetration in addition to pulsating frequency and pattern, and thus suggest the possibility of monitoring the hybrid pulsed weld penetration via arc sensing.
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